Th e decades-long debate over reusable launch vehicles (RLVs) versus expendable launch vehicles (ELVs) has been less a reasoned debate than a sustained argument for the building of reusable launchers instead of the standard throwaway rocket. The single greatest touted advantage of reusable launch vehicles is that they reduce launch costs.' Comparing reusable and expendable rockets is not simple; it is a rather complicated task not unlike the proverbial comparing of apples and oranges. To compare the costs of the two types of rockets, we must consider two types of costs, recurring and nonrecurring. Nonrecurring costs entail those funds spent on designing, developing, researching, and engineering a launcher (called DDR&E costs). Recurring costs fall into two categories: expenses for building the launcher and the costs of its operation and maintenance. Outlays for designing, developing, researching, and engineering reusable launchers are necessarily higher than those for expendable launchers because reusable rockets are technologically more challenging. For example, a reusable launch vehicle must have advanced heat shielding to allow it to reenter the atmosphere not once, but many times.Throwaway rockets have no need for such heat shielding. In addition, we possess a profound knowledge of expendable rocket technologies thanks to our long experience (over a half of a century) with ICBMs and other single-use rockets, while many of the technologies needed to build a fully reusable launcher remain in the elusive future. Construction costs, however, favor reusable launchers. For each launch, the cost of building a new expendable rocket is a recurring expense. For reusable launchers, construction costs are part of the upfront costs amortized over each launch. Because reusable launch vehicles must fly many times in order to amortize startup costs, they have to be a lot more reliable than throwaway rockets, as well as more robust, so that on any given flight the craft does not suffer significant deterioration. The reliability of throwaway launchers is about 95 percent, that is, on average, 1 launch in 20 fails. A reusable launcher with equal reliability would not be able to recoup the higher investment needed to develop and build it. Achieving the necessary increased robustness and reliability also increases the cost and decreases the useful payload weight for reusable launchers.

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